Patent application title: ROLL COUPLING TRAILER HITCH ASSEMBLY

Abstract:

A roll coupling assembly includes a roll torque transfer structure and an
alignment mechanism. The torque transfer structure includes a first load
bearing structure mountable to the rear of the tow vehicle, and a second
load bearing structure mountable to the front of the trailer drawbar.
Corresponding first and second load bearing surfaces cooperate so as to
releasably mate with one another for towing of the trailer behind the tow
vehicle. The bearing surfaces are distributed across a substantially
planar interface between the rear of the tow vehicle and the front of the
trailer drawbar so as to distribute to the tow vehicle torque imparted to
the drawbar by relative rolling motion between the trailer and tow
vehicle. The coupling alignment mechanism adjusts the relative
orientation of the first and second load bearing surfaces so as to align
them for mating to one another.

Claims:

1. A roll coupling system for roll coupling the drawbar of a trailer to
the rear of a tow vehicle, the system comprising: a roll torque transfer
structure including at least one first load bearing surface on a first
load bearing structure mountable to the rear of the tow vehicle and
adapted to be mounted closely adjacent thereto, and at least one second
load bearing surface on a second load bearing structure mountable to the
front of the trailer drawbar, wherein said first and second load bearing
surfaces cooperate so as to releasably mate with one another for towing
of the trailer behind the tow vehicle and, when the trailer is so mated
to the tow vehicle, are distributed across a substantially planar
interface between the rear of the tow vehicle and the front of the
trailer drawbar so as to distribute torque imparted to the drawbar by
relative rolling motion between the trailer and tow vehicle to the rear
of the tow vehicle by distribution of resulting moments which are
transferred to the tow vehicle so that the cumulative combined roll
resistance of the tow vehicle and trailer resist the rolling of the
trailer about the drawbar, a coupling alignment mechanism to adjust the
relative orientation of said first and second load bearing surfaces in
said substantially planar interface so as to align said first and second
load bearing surfaces for said mating with one another, wherein said
coupling alignment mechanism includes a selectively rotatable coupler,
selectively rotatable about the roll axis of the trailer drawbar, mounted
between the front of the drawbar and the rear of the tow vehicle, and
wherein said selectively rotatable coupler includes a selectively
releasable lock, and wherein said coupling alignment mechanism includes
at least one roller mounted between said first and second load bearing
surfaces to reduce wear between said first and second load bearing
surfaces.

2. The system of claim 1 wherein said first and second load bearing
surfaces include at least one V-shaped guise mating, in the V-shape of
said guise, with a corresponding pin, and wherein said at least one
roller is mounted on said pin.

3. The system of claim 1 wherein said lock locks said coupler in a fixed
roll coupling position, fixed relative to rotation about said roll axis,
upon a pre-set forward translation speed being attained by the tow
vehicle and trailer.

4. The system of claim 1 wherein said first and second load bearing
surfaces mate at least two spaced apart load transfer points on said
substantially planar interface, and wherein said planar interface is
inclined from the vertical so that an upper position of said planar
interface is tipped towards the tow vehicle so as to provide a pro-load
roll force acting on the trailer to cause the trailer to lean into a
corner, wherein an upper load transfer point is positioned forward of a
lower load transfer point of said spaced apart load transfer points.

5. The system of claim 4 wherein said male load bearing structure
includes a hook and wherein said female load bearing structure includes a
collar having an aperture sized for snug mating with said hook so as to
journal said hook in said aperture, and wherein said first and second
load bearing structures are mounted at each of said at least two spaced
apart load transfer points, and wherein said at least two spaced apart
load transfer points form a substantially linear array.

6. The system of claim 1 wherein said lock includes a male portion
interlocking into a corresponding female portion, and wherein said male
portion is urged into said interlocking with said female portion by a
default driver biasing said male portion into registry with said female
portion so that said roll coupling defaults to said locking of said
coupler to roll couple the tow vehicle and trailer together.

7. The system of claim 6 wherein said default driver includes a resilient
driver.

8. The system of claim 7 wherein said resilient driver includes a spring.

9. The system of claim 6 wherein said lock further includes a return
biasing driver for selectively unlocking said roll coupler so as to
dis-engage said roll coupling of the tow vehicle and trailer.

10. The system of claim 7 wherein said lock further includes a return
biasing resilient driver for resiliently biasing said lock to selectively
unlock said roll coupling.

11. The system of claim 6 wherein said roll coupling includes a pair of
plates, a first plate of which is adapted to be mounted to the rearmost
end of the tow vehicle, a second plate of which is adapted to be mounted
to the front end of the drawbar of the trailer, and wherein said pair of
plates are substantially flush against one another when the trailer is
coupled to the tow vehicle, and wherein said pair of plates pivot
relative to one another in flush rotation one over the other, and wherein
each plate of said pair of plates has an aperture, and wherein when said
apertures in said plates are aligned, the trailer is aligned for roll
coupling with the tow vehicle, and wherein said male portion is mounted
in one of said apertures and the other of said apertures is said female
portion.

12. The system of claim 11 wherein said male portion is an elongate
member which is projected into snug mating with said female portion to
effect said roll coupling.

13. The system of claim 12 wherein said default driver is a linear driver
biasing said member linearly into registry in said aperture of said
female portion.

14. The system of claim 13 further comprising a return driver selectively
actuable to extract said member from said female portion so as to
dis-engage said roll coupling.

15. The system of claim 14 wherein said return driver is a linear driver
extracting said member co-axially with said default driver.

16. The system of claim 15 wherein said default driver and said return
driver are resilient.

17. The system of claim 16 wherein said linear driver and said return
driver are each chosen from the group comprising a resilient spring
driver, a pneumatic driver.

18. The system of claim 14 wherein said second plate is adapted to be
mounted on the drawbar of the trailer and wherein said first plate is
adapted to be mounted to the rear of the tow vehicle.

19. The system of claim 18 wherein said roll torque transfer structure
first and second load bearing surfaces are mounted to said first plate,
opposite said second plate.

20. The system of claim 1 wherein said lock is adapted to be biased into
said locking upon receipt of a locking trigger corresponding to said
pre-set forward translation speed.

21. The system of claim 20 further comprising a locking driver locking
said lock and a return driver unlocking said lock, and wherein said
locking driver is continually biasing said lock into said fixed roll
coupling position, and wherein said return driver return biases said
locking driver so as to prevent said locking until said trigger is
received whereupon said return driver dis-engages from said return
biasing of said locking driver.

22. The system of claim 21 wherein said locking driver and said return
driver are both resilient drivers.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from United States Provisional
Patent Application Numbers:

[0002] For the United States only, this application is a
Continuation-in-Part of the U.S. application Ser. No. 12/216,981, filed
Jul. 14, 2008, entitled Roll Coupling Trailer Hitch Assembly.

FIELD OF THE INVENTION

[0003] The present invention relates to improvements in devices for
connecting a trailer to the rear of a tow vehicle so as to roll couple
the trailer to the tow vehicle to improve vehicle stability.

BACKGROUND OF THE INVENTION

[0004] In the prior art applicant is aware of U.S. Pat. No. 1,524,503,
which issued Jan. 27, 1925 to Bennett et al for Trailer Coupling, U.S.
Pat. No. 1,552,620, which issued Sep. 8, 1925 to Knox for Trailer
Coupling, U.S. Pat. No. 2,460,466, which issued Feb. 1, 1949 to Nogle for
Trailer Dolly, U.S. Pat. No. 2,360,902, which issued Oct. 24, 1944 to
Simmons for Vehicle, U.S. Pat. No. 1,957,917, which issued May 8, 1934 to
Storey for Tractor, U.S. Pat. No. 3,298,706, which issued Jan. 17, 1967
to Lyall for Heavy Motor Vehicles and Equipment, U.S. Pat. No. 1,643,885,
which issued Sep. 27, 1927 to Gill for Means for Loading and Hauling
Automobiles.

[0005] Knox and Bennett describe trailer coupling assemblies using two
vertically aligned hitch points for the purpose of automatically
elevating a trailer while connecting the trailer to the tow vehicle in
order to transfer trailer weight to the rear axle of the tow vehicle.

[0006] Nogle discloses a wheeled dolly having two horizontally aligned
connecting points to carry the weight of the front of a trailer towed
behind the dolly.

[0007] Simmons describes providing one or more connection points for the
purposes of selectively transferring weight from one portion of the
vehicle to another and to change the angular alignment of the
interconnected vehicles.

[0008] Storey discloses providing articulation to interconnect two parts
of a vehicle. Applicant is aware that in the prior art it is known to
provide booster axles designed to be attached to the front or rear of
vehicles for the purpose of transferring weight from the vehicles to the
booster axles to increase the carrying capacity of the vehicles.

[0009] By way of example, Lyall describes an articulating booster axle
designed to transfer part of a crane's weight to a booster axle that
trails or tracks behind the crane.

[0010] Gill teaches an automobile carrier with a hitch assembly located
aft of the truck frame.

[0011] Applicant has in the present invention improved on his invention
described and claimed in his United States patent application entitled
Roll coupling Trailer Hitch Assembly, filed Jul. 14, 2008, and published
Jan. 15, 2009, under publication number US2009-0014982.

[0012] As commercial vehicles increase load capacity by increasing the
number of weight bearing axles over a given length, the vehicle's centre
of gravity is raised and the vehicle becomes increasingly unstable while
in motion. In applicant's experience, the governing governmental
authorities have started to restrict weights on combination vehicles
where the trailers are attached to the rear of tow vehicles (including
dump truck and pony trailer combinations, or other truck and trailer
combinations, or combinations where a trailer is towed by another
trailer) in order to reduce the number of accidents involving these
vehicles.

[0013] In applicant's experience, at least with respect to truck and
trailer combinations, roll coupling these types of vehicle combinations
may improve safety and provide an alternative to reducing weight limits
by the governing authorities. To the knowledge of applicant, tridem (that
is, three axle) pony trailers are presently limited to 21,000 kgs on the
trailer axles in British Columbia, Canada. The previous maximum weight
for a tridem axle group in British Columbia was 24,000 kgs.

[0014] Roll coupling may provide improved yaw and roll stability where
there is roll coupling between the tow vehicle and towed trailer when
used in conjunction with sufficiently torsionally strong draw bars and
corresponding supporting framework on the trailer to resist twisting
during initial rolling motion of the trailer and so as to import the
resulting torque to the roll coupling and thence to the tow vehicle. A
single roll coupling hitch or a plurality of diagonal, horizontal or
vertically aligned hitch assemblies and contact points may be used as
required for different applications to provide roll coupling and so as to
allow legal hitch offset distances, and so as to provide redundant
critical hitch components and so as to reduce operating stresses on
individual hitch components. Using common hitch components whenever
possible also enables the tow vehicle to be used with trailers equipped
with lunette rings, that is, which are not equipped with roll couplers.

[0019] The handling performance of the loaded truck/pony trailer was
improved with roll coupling. The degree of oversteer occurring at high
lateral accelerations was reduced and the transition from understeer to
oversteer occurred at a higher lateral acceleration when roll coupling
was present. The handling performance was essentially the same for both
the non roll coupled and roll coupled trailers in combination with an
empty truck. However the roll coupled trailer exhibited less understeer
and therefore has slightly improved handling characteristics.

[0020] Stability was improved under both loading conditions with roll
coupling, enabling the static rollover performance standard of 0.35 g to
be achieved when coupled with a loaded truck.

[0021] Roll coupling resulted in an improvement dynamic performance for
all dynamic performance measures (that is, LTR, RA, and TOT as defined
below). The use of roll coupling allowed all the dynamic performance
standards to be achieved under both loading conditions. Of particular
note is the significant improvement in load transfer ratio in the order
of 28% under both loading conditions.

[0022] The low-speed performance was largely unaffected by roll coupling.
However this configuration exhibited high levels of friction demand (FD)
with and without roll coupling, particularly when the truck was unloaded.
This implies that only a loaded truck should be used to haul a loaded
trailer under low traction conditions. Even with a loaded truck care
should be taken when negotiating tight turns.

[0023] The high-speed offtracking performance standard (<0.46 m) was
achieved for both coupling methods when hauled by an empty truck. The
standard was not achieved for either coupling method when hauled by a
loaded truck, but performance was marginally better with a roll coupled
trailer.

[0024] Understeer Coefficients (USC) were used to evaluate handling
performance at steady-state conditions by calculating the understeer
coefficient at 0.15 g, 0.30 g, (TAC 0.25 g). This measure is expressed in
degrees per g which represents the slope of the handling diagram.
Positive and negative values indicate understeer and oversteer levels
respectively. This performance measure is determined during a ramp steer
manoeuvre (ramp steer rate of 2 deg/sec at steering wheel) at a forward
velocity of 100 km/h. The pass/fail criterion is addressed by comparing
the understeer coefficient with the critical understeer coefficient,
which can be expressed as -Lg/U2, where U is the vehicle speed (U=27.77
m/s (100 km/h)), L is the tractor or truck wheelbase (in metres), and g
is acceleration due to gravity (9.81 m/s2). If the value of the
understeer coefficient is greater than the critical value, the vehicle
will meet the criterion (TAC performance standard). In addition the
lateral acceleration where the transition from understeer to oversteer
(that is, the point where the understeer coefficient is zero) is also
computed.

[0025] Static Rollover Threshold (SRT) is the level of steady lateral
acceleration beyond which the configuration rolls over. The measure is
expressed as the lateral acceleration (in g's) at which all wheels on one
side, except the steer axle, lift off the ground. Configuration
performance is considered satisfactory if the static rollover threshold
is greater than or equal to 0.35 g.

[0026] Load Transfer Ratio (LTR) is defined as the ratio of the absolute
value of the difference between the sum of the right wheel loads and the
sum of the left wheel loads, to the sum of all the wheel loads. The front
steering axle is excluded from the calculations because of its relatively
high roll compliance. Configuration performance is considered
satisfactory if the LTR is less than or equal to 0.60 (TAC performance
standard). This performance measure is evaluated during a rapid lane
change manoeuvre conducted at 88 km/h, yielding a lateral acceleration
amplitude of 0.15 g and a period of 2.5 seconds at the tractor's steering
axle.

[0027] Rearward Amplification (RWA) is defined as the ratio of the peak
lateral acceleration at the mass centre of the rearmost trailer to that
developed at the mass centre of the tractor. Configuration performance is
considered satisfactory if the RWA is less than or equal to 2.0, which is
the current TAC performance standard. This performance measure was
evaluated in the same manoeuvre as LTR.

[0028] Friction Demand (FD) performance measure describes the non-tractive
tire friction levels required at the drive axles of a tractor. Excessive
friction demand is a contributing factor to jack-knife and also results
in excessive tire wear. Friction demand is the absolute value of the
ratio of the resultant sheer force acting at the drive tires divided by
the cosine of the tractor/trailer articulation angle to the vertical load
on the drive tires. Configuration performance is considered satisfactory
if FD is less than or equal to 0.1 (TAC performance standard). This
performance measure is evaluated in a 90-degree turn at a vehicle speed
of 8.25 km/h. During the manoeuvre, the centre of the front steer axle
tracks an arc with a 12.8-m radius (approximately a 14-m
outside-wheel-path radius).

[0029] Lateral Friction Utilization (LFU) is a measure proposed by NRC to
characterize the highest level of the lateral friction utilization at the
steering axle. LFU is defined as the ratio of the sum of lateral forces
to the vertical load, and the peak tire/road coefficient of adhesion. The
tires of a steering axle that achieves a lateral friction utilization
level of 1 are said to be saturated. Configuration performance is
considered satisfactory if LFU is less than or equal to 0.80 (NRC
recommended performance standard). Initially this performance measure was
evaluated on a high friction surface. This measure was modified by
evaluating LFU on low friction surfaces, which are more critical for
steering performance, by using low friction tire characteristics
(μ=0.2). This performance measure was evaluated using the same
manoeuvre as FD.

[0030] Low Speed Offtracking (LSOT) was measured as the maximum lateral
displacement of the centre-line of the last axle of the configuration
from the path taken by the centre of the steer axle. Configuration
performance is considered satisfactory if LSOT is less than or equal to
5.6 m (TAC performance standard). This performance measure was evaluated
using the same manoeuvre as FD and LFU.

[0031] High Speed Steady State Offtracking (HSOT) was measured as the
maximum lateral displacement of the centre-line of the last axle of the
configuration from the path taken by the centre of the steer axle.
Configuration performance is considered satisfactory if HSOT is less than
or equal to 0.46 m (TAC performance standard). This value represents a
minimal clearance of 0.15 m between the trailer tires and the outside of
a 3.66-m wide conventional traffic lane. This performance measure was
evaluated when the vehicle is operated in a 393-m curve radius, at a
speed of 100 km/h, thereby attaining a steady lateral acceleration level
of 0.2 g.

[0032] Transient Offtracking (TOT) was measured as the maximum lateral
displacement of the centre-line of the last axle of the configuration
from the path taken by the centre of the steer axle. Configuration
performance is considered satisfactory if TOT is less than or equal to
0.8 m (TAC performance standard). This performance measure was evaluated
in the same manoeuvre as LTR and RWA.

SUMMARY OF THE INVENTION

[0033] A roll coupling system for roll coupling the drawbar of a trailer
to the rear of a tow vehicle may be characterized as including: [0034]
a) a roll torque transfer structure including at least one first load
bearing surface on a first load bearing structure mountable to the rear
of the tow vehicle and adapted to be mounted closely adjacent thereto,
and at least one second load bearing surface on a second load bearing
structure mountable to the front of the trailer drawbar, wherein the
first and second load bearing surfaces cooperate so as to releasably mate
with one another for towing of the trailer behind the tow vehicle and,
when the trailer is so mated to the tow vehicle, are distributed across a
substantially planar interface, which may be vertical, between the rear
of the tow vehicle and the front of the trailer drawbar so as to
distribute torque imparted to the drawbar by relative rolling motion
between the trailer and tow vehicle to the rear of the tow vehicle by
distribution of resulting moments which are transferred to the tow
vehicle so that the cumulative combined roll resistance of the tow
vehicle and trailer resist the rolling of the trailer about the drawbar,
and [0035] b) a coupling alignment mechanism to adjust the relative
orientation of the first and second load bearing surfaces in the
substantially planar interface so as to align the first and second load
bearing surfaces for the mating with one another.

[0036] The coupling alignment mechanism may include at least one
self-aligning guide cooperating between the first and second load bearing
structures so as to urge relative alignment about a roll axis of the
drawbar of the first and second load bearing surfaces as the rear of the
tow vehicle and the front of the drawbar are urged together so as to urge
the first and second load bearing surfaces to the mate with one another,
wherein the coupling alignment mechanism includes a selectively rotatable
roll coupler, selectively rotatable about the roll axis of the trailer
drawbar, mounted between the front of the drawbar and the rear of the tow
vehicle, and wherein the selectively rotatable coupler includes a
selectively releasable lock, wherein the lock locks said coupler in a
fixed roll coupling position, fixed relative to rotation about said roll
axis, upon a pre-set forward translation speed being attained by the tow
vehicle and trailer.

[0037] The first and second load bearing surfaces may mate at, at least
two spaced apart load transfer points on the substantially planar
interface. The first and second load bearing structures may be mounted at
each of the at least two spaced apart load transfer points. At least one
self-aligning guide may be mounted at least one of the two spaced apart
load transfer points.

[0038] In one embodiment the planar interface is inclined from the
vertical so that an upper position of the planar interface is tipped
towards the tow vehicle so as to provide a pre-load roll force acting on
the trailer to cause the trailer to lean into a corner, wherein an upper
load transfer point is positioned forward of a lower load transfer point
of the spaced apart load transfer points.

[0039] Typically the first and second load bearing structures include male
and female load bearing structures. Further, each self-aligning guide may
include at least one substantially v-shaped guide for guiding the male
load bearing structure into mating engagement in the female load bearing
structure. Each v-shaped guide may include a spaced apart pair of
substantially v-shaped guides, where the pair of substantially v-shaped
guides may be substantially parallel and wherein each guide may include a
pair of arms forming the v-shape, and where the arms may extend
substantially orthogonally from the substantially planar interface.

[0040] In one embodiment, the male load bearing structure includes a hook
and the female load bearing structure includes a collar having an
aperture sized for snug mating with the hook so as to journal the hook in
the aperture. The hook may include a pintle hook and the collar may
include a lunette ring.

[0041] The spaced apart load transfer points may form a substantially
linear array. The array may be vertical, horizontal or otherwise aligned
in the substantially planar interface.

[0042] The lock for locking the roll coupler includes a male portion
interlocking into a corresponding female portion. In one embodiment the
male portion is urged into interlocking with the female portion by a
default driver biasing the male portion into registry with the female
portion so that the roll coupling defaults to the locking of the roll
coupler to roll couple the tow vehicle and trailer together. The default
driver alignment mechanism may include a resilient driver, for example a
spring. The lock may further include a return biasing driver for
selectively unlocking the roll rotatable coupler so as to dis-engage the
roll coupling of the tow vehicle and trailer.

[0043] The roll coupling may include in one example which is not intended
to be limiting, a pair of plates, a first plate of which is adapted to be
mounted to the rearmost end of the tow vehicle, a second plate of which
is adapted to be mounted to the front end of the drawbar of the trailer.
The pair of plates are substantially flush against one another when the
trailer is coupled to the tow vehicle. The pair of plates pivot relative
to one another in flush rotation one over the other. Each plate in the
pair of plates has an aperture. When the apertures in the plates are
aligned, the trailer is aligned for roll coupling with the tow vehicle.
The male portion is mounted in one of the apertures. The other of the
apertures is the female portion. The male portion is an elongate member
which is projected into snug mating with said female portion to effect
said roll coupling. The default driver urges the male portion, such as a
pin member or the latch member, into the female portion to lock the roll
coupler.

[0044] In one embodiment the default driver is a linear driver biasing the
member linearly into registry in the aperture of the female portion. The
return driver is, selectively rotatable about the roll axis of the
trailer drawbar, and mounted between the front of the drawbar and the
rear of the tow vehicle. Further, the selectively rotatable coupler may
include a selectively releasable lock. The lock locks the coupler in a
fixed roll coupling position, fixed relative to rotation about the roll
axis. The coupler and the lock may be mounted on the front end of the
drawbar.

[0045] The alignment mechanism may also include at least one roller
mounted on the pins so as to mate with the V-shaped guides on the load
bearing structures.

[0046] The roll coupling lock may be adapted to be biased into locking of
the roll coupling upon receipt of a locking trigger corresponding to the
pre-set forward translation speed of the truck and trailer. A default
locking driver may be provided to lock the lock and, again, a return
driver may be provided for unlocking the lock. The locking driver may
continually bias the lock into the fixed roll coupling position. The
return driver return biases the locking driver into its unlocked position
so as to prevent the locking of the roll coupling until the locking
trigger is received, whereupon the return driver dis-engages from the
return biasing of the locking driver. Again, the locking driver and the
return driver may both be resiliently biased drivers, that is they may
both be resilient drivers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In the following figures, similar characters of reference denote
corresponding parts in each view.

[0048] FIG. 1 is, a partially cutaway plan view of a first embodiment of
the roll coupling assembly according to the present invention.

[0053] FIG. 4a is, in perspective view, the roll coupling assembly of FIG.
3 with the roll coupling assembly mounted together and the drawbar
pivoted upwardly.

[0054]FIG. 4b is the view of FIG. 4a with the drawbar lowered to the
horizontal.

[0055] FIG. 4c is the view of FIG. 4b with the drawbar lowered below
horizontal.

[0056] FIG. 5a is, in perspective view, the female load transfer structure
according to a second embodiment of the roll coupling assembly according
to the present invention mounted on the rear of a tow vehicle frame.

[0057] FIG. 5b is, in perspective view, the male load transfer structure
of the embodiment of FIG. 5a mounted on the front end of a drawbar.

[0058]FIG. 6 is, in perspective view looking towards the rear of the tow
vehicle, the roll coupling assembly of FIGS. 5a and 5b.

[0059] FIG. 7 is the roll coupling assembly of FIG. 6 in perspective view
looking at the front of the drawbar.

[0060] FIG. 8 is a further embodiment of the roll coupling assembly of
FIG. 7 wherein the male load transfer structure is selectively rotatable
about the roll axis of the drawbar.

[0061]FIG. 9 is, in perspective view, a further embodiment of the roll
coupling assembly according to the present invention.

[0062] FIG. 10 is, in perspective view, the roll coupling assembly of FIG.
9 with the drawbar rotated in a horizontal plane.

[0063] FIG. 11 is, in perspective view, a further alternative embodiment
of the roll coupling assembly of FIG. 9.

[0064] FIG. 12 is, in perspective view, the roll coupling assembly of FIG.
11 with the drawbar rotated in a horizontal plane.

[0065] FIG. 13 is, in left side elevation view, a further embodiment of
the roll coupling assembly according to the present invention.

[0066]FIG. 14 is, in left side elevation view, yet a further embodiment
of the roll coupling assembly according to the present invention.

[0067] FIG. 15 is, in left side elevation view, the roll coupling assembly
of FIG. 13 adapted to provide selective roll rotation of the coupling
assembly relative to the drawbar.

[0068] FIG. 16 is, in perspective view, a further embodiment of a roll
coupling assembly according to the present invention.

[0069] FIG. 17 is a variant of the roll coupling assembly of FIG. 13
illustrated in left side elevation view.

[0070] FIG. 18 is a further variant of the roll coupling assembly of FIG.
13 illustrated in left side elevation view.

[0071] FIG. 19 is a cross sectional view along line 19-19 in FIG. 18.

[0072] FIG. 20 is, in perspective view, a further embodiment of a roll
coupling assembly according to the present invention.

[0073]FIG. 21 is, in perspective view, the roll coupling assembly of FIG.
20 with the drawbar rolled about the drawbar roll axis.

[0074] FIG. 22 is, in perspective view, the roll coupling assembly of FIG.
20, with the drawbar rotated in a horizontal plane.

[0089] FIG. 36 is, in perspective view, a further embodiment of the roll
coupling assembly according to the present invention.

[0090] FIG. 37 is, in perspective view, the locking assembly of the roll
coupling of FIG. 36, with a locking assembly in its locked position.

[0091] FIG. 38 is, in perspective view, the locking assembly of FIG. 37 in
its open position.

[0092] FIG. 39 is, in perspective view, a further embodiment of the roll
coupling assembly according to the present invention, with the alignment
forks on the drawbar removed to show how the hitch may also be used to
pull a conventional drawbar with a single lunette ring.

[0093] FIG. 40 is, in lower perspective view, a further embodiment of the
roll coupling assembly according to the present invention.

[0106] FIG. 53 is, in side elevation view, the trailer of FIG. 52 roll
coupled to a gravel truck.

[0107] FIG. 54 is, in plan view, the transfer trailer dolly of FIG. 51
with the transfer trailer dolly of FIG. 51 with the drawbar retracted.

[0108] FIG. 55 is a sectional view along line 55-55 in FIG. 54.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0109] FIGS. 1 to 4 illustrate a roll coupling hitch assembly which
includes a coupler that engages with a vertical pin to allow yaw and
pitch rotation while providing roll coupling to resist rolling about a
horizontal longitudinal axis of the trailer (not shown). FIG. 1
illustrates a top view of king pin 10 in the process of engaging with a
primary jaw 12 having spur gear teeth 12a that engage with teeth 14a on a
secondary jaw 14 to transmit motion as the king pin forces the primary
jaw lever 16 rearward until the king pin comes to rest at the rear of the
guide slot 18 in the coupler housing 20. As the primary jaw rotates
clockwise around pin 22 under pressure from the king pin, as would be the
case when a tow vehicle backs into the trailer drawbar 38, the handle 24
rotates clockwise in direction A to cause the latch 26 below the handle
as best seen in FIG. 2 to engage with a dog 28 formed in the top surface
of housing 20. This inhibits the coupler from inadvertently disengaging.

[0110] FIGS. 2a and 2b illustrate the jaw assemblies when they are open as
shown in FIG. 2a and closed as shown in FIG. 2b. FIG. 2 shows the jaw
assembly installed in the housing 20. The housing side plates are not
shown in FIG. 2. Housing 20 includes upper and lower guide plates 30
having v-shaped entryways 30a (see FIG. 3) to self-align the coupler with
kingpin 10 as the kingpin engages in the entryways during connecting in
direction B the tow vehicle to the trailer. Entryways 30a provide
self-aligning guides which allow coupling of the trailer to the tow
vehicle on uneven ground where, otherwise, the male and female coupling
structures would not readily align without for example jacking-up the
trailer on the low side. It is understood that although not shown
illustrated on all embodiments herein, it is intended that self-aligning
guides be provided on all embodiments where for example substantially
v-shaped guides may be aligned and positioned to guide lunette rings or
pins onto their corresponding pintle hooks or collars respectively.

[0111] Rolling relative movement is resisted between the tow vehicle and
trailer when the coupler is engaged with king pin 10. Kingpin 10 is fixed
on its opposite ends to a bracket 32 that attaches in the illustrated
embodiment to the tow vehicle although this is not intended to be
limiting as it is intended to be within the scope of the present
invention in this and the other embodiments taught herein that if it is
taught that the pin is on the trailer and the receiving coupler on the
tow vehicle, that the opposite arrangement is also included, for example,
that the kingpin or pins be on the trailer drawbar and the receiver on
the frame of the tow vehicle.

[0112] The lower platform 34 of bracket 32 is larger than the top plate to
support the weight of the trailer drawbar 38 and facilitate yaw rotation
when the combination tow vehicle and trailer turns a corner.

[0113] FIG. 3 illustrates the housing 20 with the side plates attached.
The side plates anchor the pitch rotation pins 36 on both sides of the
housing. The trailer drawbar 38 is pivotally attached to the housing via
pitch pins 36 so that, as seen in FIGS. 4a, 4b and 4c drawbar 38 may
pitch relative to the tow vehicle in a range of motion C around the axis
of pitch pin 36. The jaws are engaged with, and rotate around, the king
pin 10 in bracket 32 to provide yaw rotation of the drawbar relative to
the tow vehicle.

[0114] FIGS. 5 to 8 illustrate a second embodiment of roll coupling
assembly according to the present invention. The coupler is attached to
the tow vehicle as better described below instead of to the trailer. This
embodiment is particularly suitable for trucks that have an exposed frame
section at the rear of the vehicle such as logging trucks. As with the
embodiment of FIGS. 1 to 4, and other embodiments taught herein, again
advantageously the coupling assembly is closely adjacent the rear of the
tow vehicle so as to reduce interference at the back of the tow vehicle.
For example, in the first embodiment, if the tow vehicle is a dump truck
then interference with a load being dumped from the truck box is
minimized, that is, the load doesn't directly pour on to the coupler.

[0115] The truck frame rails 40 are attached to a rear cross member 42
that is used to hold the hitch bracket 44 in place. The hitch bracket may
be attached directly to the cross member or alternatively it may be
cushioned with rubber blocks 46 to absorb shock and permit limited
movement to avoid stressing hitch components when operating in rough
terrain. However it is attached, the bracket provides upper and lower
guide plates 30 again with v-shaped guides 30a to self-align the coupler
with the king pin 10 when the tow vehicle is being connected to the
trailer and to resist relative rolling movement about longitudinal axis D
(FIG. 8) between the tow vehicle and trailer. Someone skilled in the art
would know of many different ways to lock the trailer king pin(s) 10
within the neck 30b of guide plates 30 without restricting yaw movement.
In this embodiment, two jaws 48 are provided in locking device 50.
Locking device 50 holds the jaws open or closed. When open, the jaws do
not obstruct guides 30a or neck 30b. As seen in FIG. 5b, the forward end
of the trailer drawbar 38 has kingpin 10 mounted vertically thereon.
Kingpin 10 runs vertically through a metal block 52 that also houses the
pitch pin 36 to provide pitch rotation of the drawbar about the pitch pin
axis.

[0116] FIGS. 6 and 7 further illustrate the hitch assembly of FIG. 5. The
jaw locking mechanism is shown in both views. The lock handle 50 rotates
in direction G within a pin boss 51 attached to the distal end of a leaf
spring 54 so as to unhook arm 50a from behind bracket 30c. Spring 54 is
attached at its opposite end to the upper jaw 48 by means of bracket 54a.
Moving and locking the handle 50 in either direction E deflects the
spring in direction F applying spring pressure on to upper jaws 48 to
either open or close. Both jaws are rigidly connected via pin 56 so
operation of upper jaw 48 simultaneously operates lower jaw 48. The upper
jaw 48 is held open by engaging arm 50b within latch 30d by pulling back
on, and rotation of handle 50.

[0117] FIG. 8 illustrates the trailer drawbar attached to the tow vehicle
frame. The drawbar in this embodiment however provides a means of
selectively disabling the roll coupling to allow for roll rotation about
roll axis (longitudinal axis) D. The drawbar is allowed to roll about
roll axis pin 58 when the locking mechanism 60, latching located on both
sides of the drawbar, is disengaged by rotating the control handle 62
rearwardly. This is useful for an operator where the tow vehicle and
trailer are knowingly going to be driven, usually slowly, over rough
terrain where if the roll coupler were not de-coupled damage might occur
to the coupler, frame of the trailer, and/or frame of the tow vehicle.

[0118] The third roll coupling assembly of FIGS. 9 to 12 illustrates how a
single hitch assembly may be utilized with safety chains or the like to
achieve roll coupling.

[0119]FIG. 9 again illustrates the end of a tow vehicle (truck or
trailer) frame 40 and a cross member 42. In this embodiment a pintle hook
coupling 64 is mountable to the cross member 42. The cross member 42 also
has two slotted arms 66 extending therefrom. The trailer drawbar 38
assembly is connected with the tow vehicle by engaging a lunette ring 68
mounted on the drawbar with the pintle coupler 64. A pair of oppositely
disposed ears 72a are mounted to the drawbar under the lunette ring. The
drawbar ears 72a are attached to the slotted arms 66 using chains 70 and
hooks 74. The ears 72a are mounted to the lower part of the drawbar
directly below the center of the lunette ring by a swivel bracket 72.
Swivel bracket 72 rotates in direction H about pin 72b when the tow
vehicle turns a corner. The lower ends of the chains are mounted to the
ears. The upper ends of the chains are attached to hooks 74. Hooks 74
engage in slots 66a in slotted arms 66 as the drawbar lunette ring is
being lowered over the hook 64a of the pintle coupler 64 while the
trailer is being connected to the tow vehicle.

[0120] FIG. 10 illustrates the components of FIG. 9 as they would appear
when the tow vehicle and trailer are making a turn. The chain swivel
bracket 72 has rotated in direction H within a slot on the lower forward
end of drawbar 38. The rotation of bracket 72 avoids stressing chains 70
and hooks 74.

[0121] The chains 70 illustrated in FIGS. 9 and 10 are of sufficiently
short length so as to be tight to thereby resist roll movement about axis
D between the tow vehicle and trailer. These chains can alternatively be
attached directly to the drawbar on trailers operating in jurisdictions
where more roll movement is permitted by law.

[0122] FIG. 11 illustrates an alternative arrangement substituting link
rods 76 for chains 70. Link rods 76 are pinned to arms 66 and swivel
bracket 72 using adjustable yokes 78. FIG. 12 illustrates the alternative
arrangement of FIG. 11 as it would appear when the tow vehicle is making
a turn. Again swivel bracket 72 has rotated relative to the lower forward
end of drawbar 38 to avoid stressing the link rods 76.

[0123] The roll coupling embodiments of FIGS. 13 to 19 provide two or more
vertically aligned hitches to reduce the amount of trailer weight loaded
on each hitch and to resist horizontal shear forces acting on the hitches
resulting from roll coupling the trailer to the tow vehicle.

[0124] FIG. 13 illustrates, as an example, a vertically aligned
combination of a pintle hook 64 and a drop-pintle coupling 80 mounted to
a truck towing apron 82. Lunette rings 68 are mounted on trailer drawbar
38 by pitch plate 84. Pitch plate 84 is pivotally mounted on the end of
drawbar 38 providing pitch rotation in direction I around pitch pin 36.
Lunette rings 68 mount into hook 64 and coupling 80. Hook 64 is opened by
lifting the closing arm 64b in direction J. Coupling 80 is opened by
unlatching and dropping hook 80a in direction K.

[0125]FIG. 14 illustrates how another vertically aligned hitch
arrangement may be used to employ two pinned couplers 86 above and below
a pintle coupler 64 attached to towing apron 82 such as would be found on
a dump truck equipped for towing a tandem axle pony trailer. Pins 86a are
journalled downwardly through vertically aligned eyes in collars 86b and
through a corresponding eye in each arm 84a on pitch plate 84 interleaved
between each pair of collars 86b. Pitch plate 84 is pinned at 36 to allow
pitch motion.

[0126] FIG. 15 illustrates a combination of a pintle hook 64 and a
drop-pintle coupling 80 connected to a trailer drawbar 38 via pitch plate
84 that is pinned by pitch pin 36 to a longitudinal roll axis pin 88. Pin
88 may be locked to prevent roll motion or released to allow for roll
motion about axis D to selectively provide roll coupling when desired by
an operator, for example when travelling on a highway. In the example of
a lock for pin 88, a roll lockout handle 90 rotates vertically in
direction L around a pin 92 passing through the lockout handle 90 and
trailer drawbar bracket 94 to disengage the locking flange 90a of lockout
handle 90 from a slot 88a in the end of the roll axis pin 88 for off-road
use of the tow vehicle and trailer. A safety pin 96 may be inserted
through the lockout handle bracket 94 attached to the trailer drawbar 38
and lockout handle 90 to hold the lockout handle in either its open or
closed position.

[0127] A proximity sensor or electric switch (such as sensor 38a) in FIG.
15 should be provided to activate a warning device in the cab of the tow
vehicle so as to alert the operator that the roll coupling lock has not
been engaged.

[0128] In FIG. 15 the roll lockout handle 90 is illustrated in the locked
position. In FIG. 16 the handle 90 is illustrated disengaged from slot
98a in a roll swivel pin assembly 98 mounted on roll axis pin 88 to
provide unrestricted roll movement when operating the vehicle off road on
rough and uneven terrain.

[0129] FIG. 16 illustrates the roll coupling assembly of FIG. 15 with the
addition of a yaw dampening cylinder 100 pivotally attached to drawbar 38
and connected to a second pintle coupler 64 attached to tow apron 82
laterally offset from the first pintle coupler 64 and coupling 80 so as
to control rearward amplified sway around the yaw axis on combination
vehicles having multiple trailers such as those known conventionally as
"A" trains and triples.

[0130] There are concerns in the trucking industry regarding the loss of
steering tire friction on tri-drive trucks when the frame is loaded aft
of the driving axles. FIG. 17 illustrates a fluid cylinder such as
pneumatic cylinder 102 that is pivotally anchored to the trailer drawbar
38 by pin 104. The cylinder 102 is pivotally connected to the pitch plate
bracket 84 by pin 106 to apply forward pressure on the upper coupler 64
when the cylinder is sufficiently charged to transfer weight forward of
the driving axle group to the steering axle of the tow vehicle such as
the steering axle of a ti-drive truck.

[0131] On occasion it may be necessary to move a trailer with a tow
vehicle that is not equipped for roll coupling. A pin 108 may be inserted
through an aperture in the pitch plate bracket 84 and through trailer
drawbar 38 to prevent pitch rotation around pitch pin 36 when the trailer
is attached to a tow vehicle that is equipped with only one coupler.

[0132] FIG. 18 illustrates a means of cushioning torsional shock and
restricting roll rotation on torsionally rigid trailers. The drawbar 38
has two vertical plates 110 attached at the upper and lower quadrants of
the round tube of the drawbar 38 to apply pressure on the four rubber
blocks 112 contained inside the shock dampening roll housing 114 as
better seen in the sectional view of FIG. 19 when rotational movement
occurs around the roll axis D in the center of the drawbar tube 38. The
four rubber blocks 112 are provided to cushion and resist roll rotation
in direction M of the drawbar assembly 38 within the confines of the roll
housing 114. The housing assembly is held in place using three or more
mounting bolts 116 passing through slotted holes in the drawbar 38 to
prevent excessive roll rotation. It is understood that a variety of
methods for reducing torsional shock and strain may be employed by
someone skilled in the art and that cushioning the mounting bracket on
the tow vehicle could alternatively provide similar torsional stress
relief.

[0133] The coupling embodiments of FIGS. 20 to 26 illustrate how two or
more horizontally aligned hitches may be used to achieve the roll
coupling according to the present invention.

[0134] FIG. 20 illustrates three pintle hook couplers 64 mounted to the
end of a truck or trailer frame 40 and in particular to cross member 42.
The center pintle hook connects with the centre lunette ring 68. The
centre lunette ring 68 is mounted to housing 118. Beam 120 is mounted to
housing 118 by roll axis pin 122 for rotation about axis D. Pin 124 is
mounted through corresponding apertures in housing 118 and beam 120 to
prevent roll rotation about pin 122. Pin 124 may be removed to allow roll
rotation. The beam 120 has a laterally spaced apart pair of lunette rings
68 attached to the front of each end of beam 120 to engage with the
corresponding pintle couplers 64 attached laterally spaced apart on the
tow vehicle. The three horizontally aligned pintle couplers 64 allow
pitch rotation about axis N. The trailer drawbar 38 is pivotally
connected to the housing 118 by kingpin 10 to provide yaw rotation around
king pin 10.

[0135]FIG. 21 illustrates the components of FIG. 20 as they would appear
with pin 124 removed from its aperture 124a in housing 118 and the
drawbar 38 rolled to the right about axis D. FIG. 22 illustrates those
same components with pin 124 replaced as they would appear when the tow
vehicle and trailer are making a very sharp right turn or the tow vehicle
is backing up and jack-knifing the trailer to the right so as to rotate
the drawbar about the kingpin.

[0136] FIG. 23a illustrates a further alternative embodiment. A shaft 126a
(shown in FIG. 23b) runs along axis D through beam 120. The centre
lunette ring 68 is mounted to the front of shaft 126a and yoke 126 is
mounted to the rear end. Yoke 126 is thus pivotally mounted to beam 120
for rotation around axis D and pivotally mounted to drawbar 38 by kingpin
10 to provide yaw rotation around kingpin 10. A pin such as 128 may be
journalled through aperture 126b when aligned with a corresponding
aperture in beam 120 so that pin 128 is inserted through both apertures
when yoke 126 is vertical so as to selectively lock yoke 126 to prevent
roll rotation and thus provide roll coupling. As is the case with other
embodiments, the hitch assembly may be symmetrical as shown for example
in FIG. 23a or asymmetric (that is, extending only to one side of axis D)
as illustrated in FIG. 23b.

[0137] FIGS. 24 to 26 illustrate how horizontally aligned hitches may be
used to roll couple an "A" train dolly.

[0138] FIGS. 24 and 25 illustrate the roll coupling assembly of FIG. 20
mounted to the rear end of a tow vehicle (truck or trailer) frame 40 on
cross member 42. A second pair of lunette rings 130 are mounted laterally
spaced apart to the back of beam 120. Yaw rotation about kingpin 10 may
be selectively prevented by attaching a pair of criss-crossed chains 131
or other elongate mechanical bracing means diagonally between lunette
rings 130 and a third pair of lunette rings 132 mounted on the dolly
frame 134. The chains are removed when it is desired to travel and
provide for yaw rotation about kingpin 10 as seen in FIG. 26.

[0139] Some tuck/trailer combinations use 5th wheels mounted aft of
the truck frame to attach the trailer to the truck. 5th wheel
hitches are bulky and their design inherently provides roll coupling
between two vehicle units. One disadvantage of using 5th wheels in
this configuration is that the excessive hitch offset distance decreases
yaw stability and steering traction. A second disadvantage is that the
truck and trailer frames are unnecessarily stressed when operating the
vehicle on uneven terrain and a third disadvantage is that it is
difficult to connect and disconnect the trailer on uneven terrain.

[0140] FIG. 27 illustrates a truck hitch assembly 210 that could be
attached to the rear of a truck via a towing apron 212. The truck hitch
assembly is connected to a trailer hitch assembly via two vertical pins
214 to provide yaw rotation and the trailer hitch assembly will in turn
be attached to the front of a trailer drawbar. The trailer hitch in this
illustration is connected to the truck hitch assembly via pins 214
passing through two lunette rings 216 that are attached to a pitch
bracket 218 that rotates around a pitch pin 220. The pitch pin connects
the pitch bracket to the roll bracket 222 that is pivotally attached to
the roll housing 224 via roll pin 226. The roll assembly rotates in
direction P about axis of rotation Q up to 15 degrees in either direction
suspended on plates 230 and 231 within the confines of the roll housing.
Plates 230 and 231 are mounted to collars 230a and 231a respectively. The
pin 226 is journalled through the collars and through sleeve 226a
extending therebetween. Sleeve 226a is welded to top plate 224b of
housing 224. The roll assembly may be selectively locked in a vertical
position by engaging roll lockout pin 228 with the front plate 230 of the
roll assembly. The roll lockout pin 228 slides horizontally through
sleeve 232 that is welded in forward end of the lower plate 224a of the
roll housing. Linkage 234 connects the roll lockout pin 228 to the roll
lockout handle 236 via a roll lockout arm 238 and axle 240. Rotating
handle 236 in direction R rotates axle 240 and arm 238 in direction R'
thereby draining linkage 234 in direction R''. Pulling linkage 234 in
direction R'' compresses spring 234a against slide 234b thereby urging
slide 234b in direction S. Slide 234b is connected to pin 228. Pin 228
thus is extracted from plate 230 as the slide moves in direction S. The
return of handle 236 urges pin 228 to re-engage plate 230 under the
return biasing force of spring 234c.

[0141] FIG. 28 illustrates another view with an alternative hitch
configuration using two pintle couplers 242 in place of the hitch
assembly 210.

[0142] FIG. 29 provides a better view of the roll lockout pin (228) and
sleeve (232) welded in the lower plate of the roll housing.

[0143] FIG. 30 illustrates the roll lockout linkage 234 in a section view
with right side of the roll housing removed. The lockout pin 228 is
illustrated in the "locked" position. A proximity sensor or electrical
switch 244 may be installed to warn the truck driver when the roll
coupling is disengaged.

[0144] FIG. 31 illustrates an alternative embodiment of the invention in a
section view with the right side of the roll housing removed. This
embodiment uses compressed air bellows 246 to engage a locking device 248
with the forward plate 230. Alternatively electric or hydraulic actuation
may also be employed to engage a locking device. The locking device 248
is illustrated in the "disengaged" position. The locking device may be
remotely activated either manually or automatically when the trailer
reaches an adjustable predetermined speed. A proximity sensor 244 and
adjustable trigger plate 250 cooperate to alert the truck driver when the
locking device is disengaged.

[0145] FIG. 32 illustrates a truck hitch assembly 310 with guide plates
312 that may be attached to the rear of a truck via a towing apron 314.
The trailer hitch in this embodiment is connected to the truck hitch
assembly via pins 316 passing through a pitch bracket 318 that rotates
around a pitch pin 320. The pitch pin connects the pitch bracket to the
roll bracket 322 that is pivotally attached to the drawbar 324 via front
plate 328. The roll bracket rotates up to 15 degrees in either direction
within the confines of the slots 328a provided in the front plate 328 of
the drawbar. Bolts 326 in plate 330 pass through slots 328a so as to
anchor the roll bracket to the drawbar assembly. The roll bracket may be
selectively locked in a vertical position by engaging roll lockout dog
332 with the front plate 328 and the roll bracket 322. The roll lockout
dog 332 is mounted on a shaft 334 connected to the roll lockout handle
336. The dog is centered in the drawbar with two spacers 338.

[0146] FIGS. 36-38 illustrate alternative trailer hitch components in both
the "locked" and "unlocked" positions. This embodiment provides a yaw pin
boss 340 bored to accept a yaw pin 316 to attach the trailer hitch to the
truck hitch assembly similar to the truck hitch illustrated in FIGS.
32-35. The yaw pin boss is pivotally connected to the roll housing 342
via pins 344 to permit up to 15 degrees of roll rotation in direction T
about axis U when the locking plates 346 are extended to the unlocked
position by rotating nut 348 in direction "V". The roll housing is
pivotally connected via pins 350 to the trailer drawbar 324. Housing 342
is free to rotate in direction T independently of rotation of nut 348 in
direction V.

[0147] There are occasions when vehicles operating on rough terrain should
not be roll coupled. For instance, when the loaded trailer of a logging
truck slips over a steep bank along the road the operator of the logging
truck would prefer to allow the trailer to be free to roll completely 360
degrees relative to the truck so as to dump the load of logs from the
trailer bunks before the truck is also dragged over the edge. One
embodiment of the present invention provides a means for selectively or
automatically engaging and disengaging roll coupling components to
provide roll articulation when operating on uneven terrain and roll
coupling when operating the vehicle on the highway.

[0148] FIG. 39 illustrates a truck frame 410 attached to a tow apron 412
as would be used on a dump truck. If this was the case the gravel box
would be pinned 414 at the top of the apron assembly. Attached to the tow
apron 412 is a hitch designed to pull trailers equipped with lunette
rings 416 and trailers with roll coupling hitches. The hitch assembly on
the truck or tow vehicles has a front plate 418 attached to the apron
412. The front plate 418 is attached to a top plate 420 and three smaller
plates 422 that are in turn attached to an upper pin boss 424 and a lower
pin boss 426 bored out to accept a yaw pin 428. Pin bosses 424 and 426
may be fitted with rollers 425 to reduce wear between the pin bosses and
alignment forks 440 and 442 (shown in FIG. 40). The pin bosses are welded
to their corresponding plates 420, 422. The rollers are steel collars
which are free to rotate around the pin bosses. The vertical alignment of
the pin bosses may be parallel to the apron 412 to allow the trailer
hitch assembly to rotate freely around the yaw axis or the pin bosses may
be tipped (for example about five degrees) slightly forward towards the
tow apron 412, so that an angle a between the centroidal axis through the
pins and the horizontal may be about 85 degrees, to provide a pre-load
roll force that will cause the trailer to lean into the corner. A
no-slack slider 430 is provided to provide constant pressure on the
drawbar eye or lunette ring 416.

[0149] FIG. 40 illustrates the same truck configuration attached to a
trailer drawbar 432 with a mating roll coupling hitch assembly. This
drawing illustrates a spring loaded pneumatic service chamber 434 that is
used to apply constant pressure on the no-slack slider 430 illustrated
clearly in FIG. 39. The trailer is connected to the truck hitch via the
draw eye 436 using yaw pin 428. The draw eye is part of the Pitch
assembly 438 equipped with two alignment forks 440 and 442 that engage
with the upper and lower pin bosses 424 and 426 respectively. The
alignment forks 440 and 442 serve three purposes. They guide the trailer
hitch into position when connecting the tow vehicle to the trailer, they
hold the hitch in position to enable the yaw pin 428 to be easily
inserted or withdrawn and they communicate trailer roll motion to the tow
vehicle. The pitch assembly 438 is pivotally connected with the roll
assembly 444 via the pitch pin 446. The roll assembly 444 permits the
trailer to oscillate on the roll axis unless the roll lockout pin 448 is
engaged with the roll assembly front plate 450 and the roll housing 452
and roll housing front plate 454. The roll housing is equipped with an
assess port 456 to accommodate service hoses and wires 458 that pass
through the drawbar 432 to the trailer body (not shown).

[0150] FIG. 41 provides a better view of how the roll assembly 444 is
pivotally connected with the roll housing 452 that is attached to the
trailer drawbar 432.

[0151] FIG. 42 is a cut-a-way view of the trailer hitch as the concept
could be applied to trailers designed to be pulled behind gravel trucks.
This drawing better illustrates how the pitch assembly 438 is pivotally
connected with the roll assembly 444 via pitch pin 446. The roll assembly
444 in turn is pivotally connected with the roll housing 452 via roll pin
460. This drawing also illustrates a spring loaded service chamber 434
that by default forces the roll lockout pin 448 housed in a pin boss 464
in the roll housing 452 forward through a hole journalled through the
front plate of the roll assembly 450 and finally through a hole
journalled through the roll housing front plate 454 to selectively
prevent the roll assembly 444 from rotating around roll pin 460. Spring
loaded service chamber 434 contains a spring 434a (shown by way of
example diagrammatically in dotted outline) which urges pin 448 in
direction W against the return biasing force of pneumatic bellows 434b
which, when inflated, collapse spring 434a thereby extracting pin 448 in
a direction reverse to direction W, unlocking the roll coupling.
Pneumatic inlet 434c is on the forward side of service chamber 434 to
illustrate that pin 448 locks out roll rotation, i.e. locks the roll
coupling, under spring pressure from spring 434a. When pin 448 is under
the spring pressure, the roll coupling will lock as soon as the holes in
the front plate of the roll assembly and in the roll housing front plate
align with the pin boss.

[0152] The spring loaded service chamber 434 may be manually activated by
the operator at any speed to roll couple the vehicle but if the driver
forgets to lock out roll rotation manually, the lockout pin 448 will
engage automatically under spring pressure the release of which so as to
engage the roll coupling is controlled by the antilock braking system
module of the trailer (for example as the antilock system activates at
its preset speed) or alternative means when the vehicle reaches a preset
road speed (for example 30 kilometers per hour). The operator may
selectively disengage the roll lockout pin 448 pneumatically but only
when the vehicle is travelling below the safety threshold speed.

[0153] FIG. 43 illustrates the same concept in an alternative embodiment
as it could be applied to trailers with straight drawbars such as
dollies, pony trailers and full trailers including those that are
attached to logging trucks. Trucks that have long frame rails 410
extending a distance past the driving axles may need to be stiffened
using a torsion box assembly 466. The torsion box 466 and the truck hitch
468 as previously described can be attached to a lunette ring 416 via yaw
pin 428 or a trailer hitch designed to provide roll coupling.

[0154] FIG. 44 illustrates the forward section of a drawbar 432 connected
to a selective roll coupling hitch assembly 470 that when disengaged may
roll 360 degrees around the roll axis. Pitch assembly 438 is similar to
the pitch assembly illustrated in FIGS. 40-42.

[0156] FIG. 46 is a cut-a-way of the hitch assembly that illustrates how
the spring loaded service chamber 434 is connected to a knife assembly
472 that slides in a slotted guide 474 in the roll housing 452. When the
knife 472 is forced forward while the roll assembly 444 is in alignment
with the roll housing 452 the forward portion of the knife 472 engages
with a mating slot 476 in the round roll assembly tube 478. When the
knife is engaged with the upper and lower slots in the roll housing 452
and the upper and lower slots in the roll assembly 444 the trailer hitch
will be roll coupled with the tow vehicle. When the knife 472 is
disengaged from the slots in the roll assembly 444 and resting in the
slots 474 provided in the roll housing 452, the round tube 478 which is
part of the roll assembly 444 can rotate freely around the inner round
tube 480 that is welded to and part of the roll housing 452. The inner
round tube is capped with a front plate 482 that anchors a threaded bolt
484 that protrudes through a plate 486 in the forward end of the round
tube 478 of the roll assembly 444. A threaded nut 488 prevents the roll
assembly from sliding forward off the inner round tube.

[0157] As with the previous embodiment of the invention illustrated in
FIGS. 39 through 42, FIGS. 43-46 are illustrative examples of how the
present invention may be implemented. Someone skilled in the art could
find alternative methods, and these are intended to fall within the ambit
of the present invention, to assemble a rotatable roll assembly with a
trailer drawbar, selectively lock and unlock the roll coupling assembly
at a pre-set speed, and to align the roll coupling hitch assemblies while
connecting or disconnecting the trailer and the tow vehicle.

[0158] In the embodiment of FIG. 47-49, upper and lower guide plates 30
are mounted on towing apron 43. A pintle coupler 242 is mounted to towing
apron 43 between the upper and lower guide plates 30. The corresponding
lunette ring 216 is mounted to pitch bracket 218'. The pitch bracket is
mounted to the drawbar of the trailer for example by the use of a
selective roll coupling hitch assembly 470 described above, or other roll
coupling assemblies providing for selective locking of the roll coupler.
King pins 10 are mounted on the forward arms 218a' of the pitch bracket
218' and engage in guide plates 30.

[0159] Transfer trailers are used in the aggregate industry to maximize
payload and/or to deliver material into construction sites where it is
difficult to unload pony and full trailers. The unique feature about
transfer trailers is that the gravel boxes on transfer trailers are
designed to fit inside the gravel boxes on the trucks for dumping. After
the transfer trailer gravel box has been emptied, the gravel truck
straddles and backs over the trailer drawbar to position the truck
directly in front of the trailer frame to align and slide the trailer
gravel box back on to the trailer frame. This creates two problems that
contribute to vehicle instability. Firstly, in order to be able to
transfer the box from the trailer into the truck box, the transfer box
must ride high enough on the trailer to be vertically aligned with top of
the rails in the truck box. Raising the box increases the height of the
center of gravity. Secondly, the trailer box must also be narrow enough
to fit inside the truck box so in order to carry a full load, the height
of the load inside the trailer box must be increased. These design
limitations contribute to dynamic instability problems with these
trailers because the center of gravity is comparatively much higher than
with other trailers designed for hauling aggregate.

[0160] The present invention provides a means for roll coupling the
transfer trailer with the truck to improve dynamic stability. When
anchored to the truck, the roll coupling hitch prevents the trailer
drawbar from rotating around the roll axis to improve stability on the
roll axis. The second distinguishing feature of the roll coupled transfer
trailer is that the drawbar slides under the trailer to enable the truck
to back up to the front of the trailer to get into position for
transferring the trailer box in and out of the truck box. This enables
the drawbar to be manufactured from torsionally rigid material that is
too bulky for the truck to back over to reach the trailer frame. In order
to attach and detach the trailer hitch from the truck, the drawbar may be
selectively raised or lowered using the trailer hydraulic system to align
the hitch components. This invention improves productivity by enabling
the trailer to be coupled or uncoupled more quickly and improves safety
by making the combination vehicle more stable.

[0161] As seen in FIGS. 50 and 51, the dolly assembly for a transfer
trailer 500 includes a telescopic drawbar 510 telescopically mounted
through trailer coupler 512. A roll coupling hitch assembly 514 is
attached to the forward end of the drawbar. Pneumatic actuators may be
provided to lock and unlock the drawbar to telescope the drawbar from the
trailer coupler, and hydraulic actuators 632 may provide for selectively
lifting the end of the drawbar 510 to align with the hitch.

[0162] FIG. 52 illustrates a top view of a roll coupled four axle (quad)
transfer trailer 610 and FIG. 53 illustrates a side view of the transfer
trailer 610 attached to the rear of a gravel truck 612. The two vehicles
are connected together with a roll coupling hitch 614 via the trailer
drawbar 616. The trailer drawbar connects with a dolly 618 that is
pivotally connected via a turntable 620 to the trailer frame 622. The
trailer is designed to transport a trailer gravel box 624 to a job site
and then slide the trailer gravel box 624 off the trailer frame 622 and
into the truck gravel box 626.

[0163] The drawbar 616 selectively slides in direction X through a drawbar
housing 628 that is pivotally connected to the dolly 618 and the dolly
frame 630 that attaches to the turntable 620. The dolly frame 630 houses
one or more hydraulic cylinders 632 that are pivotally connected to the
dolly frame 630 for the purpose of rotating in direction Y the drawbar
housing 628 around the horizontal axis running through to center of pin
634 that also pivotally connects the walking beams 636 to the dolly frame
630.

[0164] FIG. 54 illustrates a top view of the dolly assembly with the
drawbar illustrated in the retracted position. FIG. 55 illustrates a
section view to better illustrate how the housings are assembled.

[0165] As will be apparent to those skilled in the art in the light of the
foregoing disclosure, many alterations and modifications are possible in
the practice of this invention without departing from the spirit or scope
thereof. Accordingly, the scope of the invention is to be construed in
accordance with the substance defined by the following claims.